MONTPELIER — An annual cycling race happening Sunday at Hubbard Park will benefit a new program that buys mountain bikes for at-risk girls and provides mentoring.

Now in its fourth year, the Frozen Onion Winter Bike Race is expanding to a series of three competitions beginning with Sunday’s. Organizers say all the proceeds from the series will help support Moxie Sparks, a program that began last year and provided two 11-year-old girls with Specialized mountain bikes.

“We’d go for an hour-and-a-half- to two-hour ride with them and just help them improve their skills and talk with them and see how they were doing,” said Nina Otter, whose women’s mountain biking team — Mountain Moxie — helped launch the outreach. “Neither of them had really been on a bike before.”

About 40 people attended last winter’s race, some donning costumes with wigs or Mardi Gras beads, said Onion River Sports events director Matt Williams. The registration fee covers a raffle ticket and chili afterward.

The mentoring program had pairs of Mountain Moxie team members riding on Wednesday nights at the Catamount Outdoor Family Center in Williston with two Williston Central School students. The program helps girls who might not otherwise have the chance to experience mountain biking.

At the Catamount center, some of the hills proved difficult for the girls at the start. Eventually, though, they had the skills and confidence to complete the route and also to ride longer distances within the same amount of time, Otter said.

One girl also competed in races staged by Catamount, placing first several times in co-ed races that that included some older competitors in her age group.

As part of the program, the girls were also involved in Little Bellas, a mountain biking and mentoring organization based at the Catamount center whose Sunday program drew scores of girls aged 7 to 14 this summer.

Otter said the team hopes to expand the program to four or five girls.

In the past, the Hubbard Park winter race has included some expert riders, but many people go just for the fun, showing up with clunker bikes.

Registration begins at 9:30 a.m. at the New Shelter, and the race begins at 11 a.m.

The race loop will be a mile or so, and racers can choose to ride between one and three loops. The cost is $25 on race day; preregistration at www.bikereg.com costs $20.

In previous years, there was one race, but the level of interest led to the expanded schedule of three races this winter. The next will be Feb. 3, and a third could happen March 3 if there’s enough snow cover in the park.